Line loss tester

ABSTRACT

A signal testing apparatus for testing signals includes at least one receiver that receives signals having corresponding frequencies representative of a frequency range of a wired communication link over which the signals are received. The signal testing apparatus also includes a measurer that measures a signal loss for each of the frequencies to determine whether each measured signal loss is acceptable.

This is a continuation of U.S. patent application Ser. No. 11/408,920,filed on Apr. 24, 2006, the content of which is expressly incorporatedherein by reference in its entirety.

BACKGROUND

1. Field of the Disclosure

The present disclosure generally relates to automated test equipment andmore particularly to determining the integrity of wired communicationlinks by testing for excessive signal loss at various frequencies.

2. Background Information

Numerous services are being offered over enhanced telephone networks,including broadband Internet access and high definition televisionservices, as well as conventional telephone services. Telephonyproviders enable these services typically through use of digitalsubscriber line (DSL) technology, including High Speed DSL (HDSL), VeryHigh Speed DSL (VDSL) and Asymmetric DSL (ADSL) services.

When a telephony provider branches into other markets, it is efficientto incorporate existing infrastructure to the extent possible whenprovisioning new services. For example, a VDSL provider that supportsbroadband Internet or high definition television services connects to acustomer's location through conventional public switched telephonenetwork (PSTN) infrastructure that supports VDSL, including centraloffices and twisted wire pairs extending to a customer location. Once onpremises, though, the VDSL provider may elect to use coaxial cablepreviously deployed in the customer's home or office (e.g., to supportcable television services) to distribute data and video signals tovarious receivers. However, the VDSL provider must assure that theexisting infrastructure adequately supports the requirements of allaspects of the VDSL service, especially across the wire link from thenetwork interface device (NID), which interfaces the customer networkand the PSTN, to the customer premises equipment (e.g., a router orresidential gateway) that interfaces with the various customer devices.

DSL signal loss currently is measured over wired links, such as coaxialcables, with DSL signals present on the line, indicating only an averageloss over the entire frequency range and requiring the presence of DSLsignals (e.g., from previously provisioned DSL services). Further,automated testers presently exist that enable technicians to determineelectrical resistance across coaxial cables when there is signal fromthe transmit site present on the line, for example. However, testingresistance does not provide the information necessary to determinewhether a wired link supports a frequency spectrum sufficient to enableproper functionality of a particular service, such as VDSL.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure provides the detailed description that follows byreference to the noted drawings by way of non-limiting examples, inwhich like reference numerals represent similar parts throughout severalviews of the drawings, and in which:

FIG. 1 shows a simplified block diagram of an exemplary customer'spremises configured for VDSL integration, according to an aspect of thepresent disclosure;

FIG. 2 shows a simplified block diagram of an exemplary transmitterportion of the tester, according to an aspect of the present disclosure;

FIG. 3 shows a simplified block diagram of an exemplary receiver portionof the tester, according to an aspect of the present disclosure; and

FIG. 4 shows an exemplary flow diagram of an exemplary testing method,according to an aspect of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates to a testing apparatus and method forvalidating the integrity of wiring to ensure that it is capable ofsupporting broadband telephony services, such as VDSL, before actuallyconnecting the DSL signal to the line. Generally, a transmitter isattached to one end of a portion of wiring to be tested and a receiveris attached to the other end. The transmitter sends signals at multiplefrequencies across the section of wiring, which the receiver receivesand measures the associated radio frequency (RF) power loss. Excessiveloss (e.g., in excess of 3 decibels) at any of the multiple frequenciesindicates faulty or potentially inadequate wiring across the testedportion.

An embodiment of the disclosure provides a low cost, portable electronictesting device that can be utilized by a technician installing,maintaining or servicing high speed data and voice services, forexample, on a customer's premises. The tester may also be used in thesame manner to test passive devices, such as diplexers andsplitter/baluns used for VDSL installation, to identify defectiveequipment. Further, the transmitter and/or the receiver may includeconventional resistance testing capability, enabling the technician toperform line loss as well as resistance testing across the same sectionsof wiring using a single testing tool.

In view of the foregoing, the present disclosure, through one or more ofits various aspects, embodiments and/or specific features orsub-components, is thus intended to bring out one or more of theadvantages as specifically noted below.

An aspect of the present disclosure provides an apparatus for testingintegrity of a wired communication link, such as a coaxial cable and/ora digital subscriber line (DSL) service link. The apparatus includesmultiple receivers that receive corresponding signals sent by at leastone transmitter over the wired communications link, where the signalshave corresponding frequencies within a frequency range of the wiredcommunication link, which frequencies are representative of thefrequency range. The apparatus also includes a measurer that measures asignal loss corresponding to each of the frequencies, and an indicatorthat provides an indication of whether each measured signal loss iswithin an acceptable range. In an embodiment, the apparatus may furtherinclude a resistance tester that tests an electrical resistance on thewired communication link.

The indication of whether each measured signal loss is within anacceptable range may include multiple green indicators corresponding tothe frequencies when each measured signal loss is within the acceptablerange, and/or at least one red indicator corresponding to at least oneof the frequencies when at least one of the frequencies is not withinthe acceptable range. The indication may include a visual display thatdisplays information regarding whether each measured signal loss iswithin the acceptable range.

The multiple signals sent by the transmitter may include noise generatedacross the predetermined frequency range. Each of the receivers may bepre-tuned or adjustably tuned to the multiple frequencies.Alternatively, the multiple signals sent by the transmitter may includepre-tuned or adjustably tuned frequencies, and the receivers may beconfigured to receive these frequencies.

Another aspect of the present disclosure provides an apparatus fortesting integrity of a wired communication link, configured to enableinstallation of a DSL service, such as a coaxial cable, by receiving atleast one signal transmitted through the wired communications link. Theapparatus includes multiple receivers tuned to multiple frequencies toreceive the at least one signal transmitted through the wiredcommunications link. The apparatus also includes a determiner thatmeasures signal losses corresponding to the multiple frequencies, anddetermines whether any of the signal losses exceeds a predeterminedthreshold. The apparatus further includes an indicator that indicateswhether any of the signal losses exceeds the predetermined threshold, asdetermined by the determiner. The indicator may provide a negativeindication when any of the signal losses exceeds the predeterminedthreshold, such as illuminating a light corresponding to each of thesignal losses that exceeds the predetermined threshold.

The multiple receivers may be agile receivers that are tunable to themultiple frequencies. Also, the at least one signal transmitted throughthe communications link may be noise generated across a predeterminedfrequency range, or the at least one signal may include multiple signalscorresponding to the multiple frequencies to which the receivers aretuned.

Another aspect of the present invention provides a method for testingintegrity of a wired communication link. The method includes receivingmultiple signals transmitted through the wired communication link atmultiple frequencies; measuring multiple signal losses corresponding tothe multiple frequencies; determining an amount of signal loss for eachof the multiple frequencies; and indicating when the determined amountof signal loss for any of the signal losses exceeds a predeterminedthreshold. The method may also include indicating when each amount ofsignal loss for all of the signal losses does not exceed thepredetermined threshold. The at least one signal transmitted through thecommunications link may be noise generated across a predeterminedfrequency range, and the multiple frequencies are representative of thepredetermined frequency range.

The various aspects and embodiments of the present disclosure aredescribed in detail below.

FIG. 1 shows a simplified block diagram of an illustrative environmentin which the disclosed apparatus and method may be utilized. Moreparticularly, FIG. 1 depicts a customer's premises configured for VDSLor other broadband access integration. The services are provided to thecustomer's premises over a telephony network 100, such as a publicswitched telephone network (PSTN), including integrated services digitalnetworks (ISDN), asynchronous transfer mode (ATM) networks, and thelike. A network interface device (NID) 101 connects the customer'ssystem to the local loop of the network 100.

The dashed lines 131, 132 and 133 of FIG. 1 indicate preexisting wiringin the customer's premises, which the service provider typically wantsto use, to the extent possible, in order to minimize alterations oradditions to the existing customer communications network. Line 131shows a preexisting phone line leading to an exemplary telephone 110.Lines 132 and 133 show preexisting coaxial cable, for example, used forconnecting televisions or other video receivers 121 and 122 to a cableservices provider. The coaxial cable may likewise have been used toprovide high speed Internet access to the personal computer (PC) 112,depending on the customer's particular configuration. Note that, priorto implementation of VDSL or similar broadband telephony service, thecoaxial cables 131 would not have terminated at the NID 101, but ratherwould have interfaced with a cable network (not pictured). The splitter103 indicates an example of how coaxial cable is typically installed.

In order to integrate the broadband telephony service with the variouscommunications media, a router or residential gateway 105 is added tothe customer's network. The residential gateway 105 provides theinterfaces necessary to support each type of technology used by thecustomer, converting to and from the associated formats. For example,the residential gateway 105 may include a VDSL modem for interfacingwith the network 100. Also, as shown in the example of FIG. 1, theresidential gateway 105 may include a wireless access point, such asBluetooth or 802.11g technology, enabling a wireless local area networkon the customer's premises, which would include, for example, the PC112.

It is typically desirable for the residential gateway 105 to beinstalled on a preexisting coaxial cable, such as line 132, since theresidential gateway 105 should be centrally located within the premisesand may replace, for example, an existing cable modem or router. Also, anew line 130 is usually run from the NID 100 to the existing cablenetwork, which was not previously connected to the NID 101. The new line130 may also be coaxial cable compatible with the existing lines 132 and133.

Because line 132 provides the critical link between the residentialgateway 105 and the NID 101 (via the new line 130), its integrity mustbe properly verified prior to installation of the broadband service.This is particularly important to verify when the line 132 has beenpreviously installed by another service provider and, unlike the newline 130, is of an unknown age, condition and quality. The line losstester of the present disclosure serves this purpose, and can be used todetermine the integrity of the line 132, for example, between points “A”and “B” of FIG. 1.

More particularly, the line loss tester includes a transmitter 200 and acorresponding receiver 300, exemplary embodiments of which are depictedin FIG. 2 and FIG. 3, respectively. The transmitter 200 may be attachedat point “A” and the receiver 300 may be attached at point “B,” so thatthe integrity of line 132 between these points may be quickly andefficiently evaluated by measuring RF loss, as discussed below.

Referring to FIG. 2, the transmitter 200 includes a power supply 202,which may be a nine volt battery, for example, and a 3-way switch 204.The transmitter 200 is powered down by switching the switch 204 to theOFF position 208. The other positions of switch 204 depicted in theexemplary embodiment activate a signal generator 210 and a resistancemeasurement circuit 220. When the switch 204 is in the OFF position 208,a power indicator light 206 is off, and when the switch 204 is in anyother position, the power indicator light 206 illuminates a green light,such as a green light emitting diode (LED).

In an embodiment, the signal generator 210 includes a noise generatorthat generates and transmits noise across a spectrum of frequencies,including the frequency range needed to support the telephony service.For example, standardized VDSL requires a frequency spectrum of 25 kHzthrough 8.5 MHz, which may be accommodated by coaxial cable, such as theline 132. Generating noise across the entire frequency spectrum isparticularly efficient, in that the receiver 300 can receive signalshaving any frequencies within the entire range and be able to determinethe integrity of the wired link, as discussed below.

The signal generator 210 sends signals through an adapter, such as thecoaxial output connector 216, which is connected, for example, to line132 at point “A” of FIG. 1. Different embodiments of the transmitter 200may include various additional connections, such as, for example, anRJ11 connector to plug into phone jacks, a set of universal clipscapable of penetrating the jacketing on twisted pair wiring orconnecting to terminals such as on the back of jacks or at theprotector, and a female 75 ohm connector for connecting to a coaxialnetwork, discussed below with respect to the resistance measurementcircuit 220.

In alternative embodiments, the signal generator 210 transmits carriersignals at different specific frequencies, which may require the signalgenerator 210 to include multiple transmitters tuned to differentcarrier frequencies. Typically, at least three carrier signals are used,e.g., having low, medium and high frequencies within the desiredfrequency range needed to support the service. However, any number ofmultiple frequencies may be incorporated in the tester without departingfrom the scope and spirit of the present disclosure. The carrier signalsmay be preset to particular frequencies, such as 25 kHz, 4.0 MHz and 8.5MHz, or the carrier signals may be adjustable for added versatility.

The transmitter 200 may also include an optional, conventionalresistance measurement circuit 220, selectable by operation of theswitch 204. This enables additional testing functionality to measureelectrical resistance on a line. For example, a low resistance, such as50 ohms or less, indicates an unusable line, while normal resistance,such as 75 ohms, indicates a usable line. When a line is unusable, theindicator light 222 illuminates a red LED, and when the line is usable,the indicator light 222 illuminates a green LED. Also, the resistancemeasurement circuit 220 enables identification of multiple lines on thecustomer premises by attaching resistors in various areas and thenconnecting the transmitter 200 to a central wiring point. As each lineis connected to the transmitter 200, a green indication by the indicatorlight 222 identifies specific lines having resistors connected at theother end. This further enables the technician to test numerous linesfrom outside the customer premises using a single testing device. Thereceiver 300 need not be attached to the other end of a wired link inorder to enable the electrical resistance testing.

FIG. 3 depicts the exemplary receiver 300 which is connected, forexample, to line 132 of FIG. 1 at point “B.” The receiver 300 includesfeatures complementary to those of the transmitter 200. The receiver 300also includes a power supply 302 and a 4-way switch 304, as well as apower indicator light 306 that illuminates a green LED when the switch304 is not in the OFF position 303.

A receiver section 309 of the exemplary receiver 300 includes threereceivers tuned to different frequencies selected to adequately samplethe range of frequencies needed to determine the integrity of the wiredlink. In the example of FIG. 3, a first receiver 310 is tuned to a lowfrequency, such as 25 kHz, a second receiver 312 is tuned to a mediumfrequency, such as 4.0 MHz, and a third receiver 314 is tuned to a highfrequency, such as 8.5 MHz, to adequately cover the entire frequencyspectrum for VDSL services. However, any number and value of multiplefrequencies may be incorporated without departing from the scope andspirit of the present disclosure, so long as the frequencies adequatelyrepresent the required range to make an accurate determination of lineintegrity. The receiving section 309 receives signals transmitted by thesignal generator 210 of the transmitter 200 through an adaptorcompatible with the line being tested, such as a coaxial outputconnector 316.

In alternative embodiments, the receivers 310, 312 and 314 may bepre-tuned receivers configured to receive specific, predeterminedfrequencies, or they may be agile receivers capable of being tuneddynamically to receive any frequencies within the desired range. Thefrequencies are dependant on the configuration of the transmitter 200.For example, the embodiment in which the signal generator 210 sendsgenerated noise across a frequency spectrum, which is the simplest toimplement, the frequencies of the receivers 310, 312 and 314 do not needto match any particular frequency of the transmitter 200. Thefrequencies need only be within the frequency spectrum and adequatelyrepresentative of the range required to determine line integrity.However, when the signal generator 201 sends signals on specificdifferent frequencies, either pre-tuned or variable, each of thereceivers 310, 312 and 314 must likewise be tuned to receive carriers onthese same frequencies for the tester to function properly.

In each embodiment, the receiver section 309 measures the power of thesignals received by each of the receivers 310, 312 and 314 anddetermines whether the RF level is below a predetermined threshold, suchas 3 decibels. Indicators corresponding to each of the receivers may beprovided to indicate whether the received signals are within acceptablelimits. For example, a loss level indicator light 311 illuminates a redLED when the signal received by the first receiver 310 is below thethreshold, and illuminates a green LED when the signal received by thefirst receiver 310 is acceptable. Likewise, loss level indicator lights313 and 315 provide visual indications corresponding to the signalsreceived by the second receiver 312 and the third receiver 314,respectively. Any indication of acceptable and unacceptable signallevels, such as displayed symbols or audible tones, may be incorporatedinto the tester without departing from the scope and spirit of thedisclosure.

The exemplary receiver 300 also includes a calibration mode 307, whichis selected by operation of the switch 304. The calibration mode 307enables the receiver 300 to be calibrated with the transmitter 200 priorto testing, in order to assure that the receiver section 309 knows thepower and, when necessary, the frequencies at which signals are sent bythe signal generator 210. The calibration may be accomplished, forexample, by directly connecting the transmitter 200 and the receiver 300through a short piece of coaxial cable.

Further, the exemplary receiver 300 includes an optional resistancemeasurement circuit 320 and corresponding indicator light 322. Theresistance measurement circuit 320 is independent of the resistancemeasurement circuit 220 of the transmitter 200, and is provided as aconvenience to the technician. In other words, electrical resistance ofvarious lines may be tested in conjunction with line loss using eitherthe receiver 300 or the transmitter 200, depending on user preference.The functionality of the resistance measurement circuit 320 is the sameas that described above with respect to the resistance measurementcircuit 220. Also, like the transmitter 200, different embodiments ofthe receiver 300 may include various connections, such as, for example,an RJ11 connector to plug into phone jacks, a set of universal clipscapable of penetrating the jacketing on twisted pair wiring orconnecting to terminals such as on the back of jacks or at theprotector, and a female 75 ohm connector for connecting to a coaxialnetwork, discussed above with respect to the resistance measurementcircuit 320.

As previously disclosed, the transmitter 200 and the receiver 300 areused together to efficiently test the integrity of a wired link, amethod of which is depicted in the exemplary flow diagram of FIG. 4. Atstep s402, the transmitter 200 and the receiver 300 are connected atopposite ends of the link to be tested. For example, the transmitter 200is connected at point “A” and the receiver 300 is connected at point “B”of line 132 in FIG. 1 in order to test the level of line loss acrossthat portion of line 132. At step s404, the transmitter 200 generatesnoise to be transmitted across a range of frequencies, or at least onecarrier at a specific frequency, which is then transmitted across thewire link at step s406.

The receiver 300 receives the generated signals at step s408, anddetermines whether the RF loss across the line being tested isacceptable to enable support of the desired services. The receiversection 309 includes multiple receivers, such as the first receiver 310,the second receiver 312 and the third receiver 314, each of which aretuned for different frequencies. At step s410, it is determined whetherthe signal level corresponding to the frequency received by the firstreceiver 310 is within limits. If YES, a green LED is illuminated atstep s412; if NO, a red LED is illuminated at step s414. At step s420,it is determined whether the signal level corresponding to the frequencyreceived by the second receiver 312 is within limits. If YES, a greenLED is illuminated at step s422; if NO, a red LED is illuminated at steps424. At step s430, it is determined whether the signal levelcorresponding to the frequency received by the third receiver 314 iswithin limits. If YES, a green LED is illuminated at step s432; if NO, ared LED is illuminated at step s434. When the three green indicators areilluminated, the wire link is acceptable.

Although FIG. 4 depicts a particular sequence of steps, it is understoodthat the sequence is exemplary to an embodiment, and is not intended tobe limiting. For example, in alternative embodiments, the order of thesteps may differ, the various steps may occur simultaneously, or thenumber of frequencies being tested may vary without affecting the scopeand spirit of the disclosure. Also, although depicted linearly, thevarious embodiments may be implemented through various programmingtechniques with appropriate arrangements.

Although the present specification describes components and functionsthat may be implemented in particular embodiments with reference toparticular standards and protocols, the invention is not limited to suchstandards and protocols. Each of the standards, protocols and languagesrepresent examples of the state of the art. Such standards areperiodically superseded by faster or more efficient equivalents havingessentially the same functions. Accordingly, replacement standards andprotocols having the same or similar functions are consideredequivalents thereof.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those of skill in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope and spirit of thedisclosure. Additionally, the illustrations are merely representationaland may not be drawn to scale. Certain proportions within theillustrations may be exaggerated, while other proportions may beminimized. Accordingly, the disclosure and the figures are to beregarded as illustrative rather than restrictive.

One or more embodiments of the disclosure may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to voluntarily limit the scope of thisapplication to any particular invention or inventive concept. Moreover,although specific embodiments have been illustrated and describedherein, it should be appreciated that any subsequent arrangementdesigned to achieve the same or similar purpose may be substituted forthe specific embodiments shown. This disclosure is intended to cover anyand all subsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b)and is submitted with the understanding that it will not be used tointerpret or limit the scope or meaning of the claims. In addition, inthe foregoing Detailed Description, various features may be groupedtogether or described in a single embodiment for the purpose ofstreamlining the disclosure. This disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may be directed toless than all of the features of any of the disclosed embodiments. Thus,the following claims are incorporated into the Detailed Description,with each claim standing on its own as defining separately claimedsubject matter.

The above disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments that fall within thetrue spirit and scope of the present disclosure. Thus, to the maximumextent allowed by law, the scope of the invention is to be determined bythe broadest permissible interpretation of the following claims andtheir equivalents, and shall not be restricted or limited by theforegoing detailed description.

Although several exemplary embodiments have been described, it isunderstood that the words that have been used are words of descriptionand illustration, rather than words of limitation. Changes may be madewithin the purview of the appended claims, as presently stated and asamended, without departing from the scope and spirit of the invention inits aspects. Although the description refers to particular means,materials and embodiments, the invention is not intended to be limitedto the particulars disclosed, but rather extends to all functionallyequivalent structures, methods, and uses such as are within the scope ofthe appended claims.

1. A signal testing apparatus for testing signals, comprising: at leastone receiver that receives a plurality of signals having a correspondingplurality of frequencies representative of a frequency range of a wiredcommunication link over which the plurality of signals are received; anda measurer that measures a signal loss for each of the plurality offrequencies to determine whether each measured signal loss isacceptable.
 2. The signal testing apparatus according to claim 1,further comprising: an indicator that provides indication of whethereach measured signal loss is acceptable.
 3. The signal testing apparatusaccording to claim 2, wherein the indicator indicates whether eachmeasured signal loss is within an acceptable range.
 4. The signaltesting apparatus according to claim 2, wherein the indicator indicateswhether each measured signal loss exceeds a predetermined threshold. 5.The signal testing apparatus according to claim 2, wherein the indicatorprovides an audible indication of whether each measured signal loss isacceptable.
 6. The signal testing apparatus according to claim 2,wherein the indicator provides a visual indication of whether eachmeasured signal loss is acceptable.
 7. The signal testing apparatusaccording to claim 6, wherein the indicator provides a first colorindication to indicate whether each measured signal loss is acceptable,and wherein the indicator provides a second color indication to indicatewhether each measured signal loss is not acceptable.
 8. The signaltesting apparatus according to claim 1, wherein the at least onereceiver comprises a plurality of receiving components of a singleintegrated testing device.
 9. The signal testing apparatus according toclaim 1, wherein the plurality of signals are received from atransmitter and comprise noise generated across the frequency range bythe transmitter.
 10. The signal testing apparatus according to claim 1,wherein each of the at least one receiver is pre-tuned to the pluralityof frequencies.
 11. The signal testing apparatus according to claim 1,wherein each of the at least one receiver is adjustably tuned to theplurality of frequencies.
 12. The signal testing apparatus according toclaim 1, wherein the wired communication link comprises a digitalsubscriber line service link.
 13. The signal testing apparatus accordingto claim 1, wherein the wired communication link comprises a coaxialcable.
 14. The signal testing apparatus according to claim 1, furthercomprising: a resistance tester that tests an electrical resistance onthe wired communication link.
 15. The signal testing apparatus accordingto claim 9, wherein a passive device is connected to the wiredcommunication link between the signal testing apparatus and thetransmitter.
 16. The signal testing apparatus according to claim 1,wherein the signal testing apparatus measures signal loss on a wiredcommunication link between a residential gateway and a network interfacedevice.
 17. A signal testing apparatus for testing signals, comprising:at least one receiver that receives, from a tangible passive device, aplurality of signals having a corresponding plurality of frequenciesrepresentative of a frequency range of the passive device; and ameasurer that measures a signal loss for each of the plurality offrequencies to determine whether each measured signal loss isacceptable.
 18. The signal testing apparatus according to claim 17,wherein the at least one receiver comprise agile receivers that aretunable to the plurality of frequencies.
 19. A method for testingsignals, comprising: receiving, by at least one receiver, a plurality ofsignals having a corresponding plurality of frequencies representativeof a frequency range of a wired communication link over which theplurality of signals are received; and measuring a signal loss for eachof the plurality of frequencies to determine whether each measuredsignal loss is acceptable.
 20. The method for testing signals of claim19, further comprising: indicating, by an indicator on the receiver,whether each measured signal loss is acceptable.